The present invention relates to a vacuum breaker that includes a feature that enables the breaker to resist spillage of water out of the top of the valve. Vacuum breaker valves are frequently used in environments such as agricultural irrigation areas to prevent back-siphonage of potentially contaminated water into a potable water supply. This prevents contamination, should the potable water system's pressure drop. A vacuum breaker typically contains a check assembly that is pressed forward by water supply pressure and covers small vent holes. Should the supply pressure drop, the check assembly springs back opening the vent holes, which let in outside air and prevent backflow of water.
During normal flow conditions, the check assembly remains open and a float seals onto a bonnet, closing the air inlet. A minimum supply pressure of 10 psi is normally required to fully close the valve. As the line pressure falls to 1 psi, a spring-loaded atmospheric vent valve opens, breaking the vacuum and thereby preventing back-siphonage.
When used in an outdoor environment, vacuum breakers frequently permit a small amount of water to be ejected out of the air inlet during the valve pressurization process, though not once pressurized. However, when the vacuum breaker is installed in a building, for example, to prevent the valve from freezing during cold weather, codes require that no water be ejected from the valve during operation.
In some instances, for example, when the valve is pressurizing slowly, the check assembly may assume a misaligned or “cocked” position relative to the axially-aligned position of the float. This misalignment may occur as a result, of a radial gap between the check assembly and the valve body due to manufacturing tolerances. As the check assembly rises to push the float up to seal the air inlet, the check assembly may maintain its misaligned position, and the float will therefore not fully seal to prevent spillage of water from the air inlet.
There is therefore a need for a simple and reliable spill-resistant vacuum breaker valve that prevents ejection of water from the air inlet during pressurization.
Therefore, it is an object of the invention to provide a spill-resistant vacuum breaker valve that will reliably prevent spillage when the check assembly is not axially-aligned with the flow axis of the valve, and in particular, with the valve float.
It is another object of the invention to provide a spill-resistant vacuum breaker valve that allows the float to freely pivot about the axis of the check assembly in order for the float to level itself to its sealing surface on the valve bonnet and seal even though the check assembly remains out of alignment as it rises.
These and other aspects of the invention are achieved by providing a spill-resistant vacuum breaker valve that includes a valve body having a water inlet, a water outlet; an air inlet and a check assembly positioned in the valve body and movable between an open position for allowing water to flow into the valve body through the water inlet and out of the valve body through the water outlet, and a closed position for preventing water from flowing out of the valve body through the water outlet. The check assembly includes a check poppet, a spring positioned on the check poppet and a spring retainer positioned over and maintaining the spring under compression on the check poppet. The spring retainer includes a co-axial pivot butt.
A float assembly is positioned in the valve body between the check assembly and the air inlet and movable by movement of the check assembly between an open position allowing air to enter the valve body through the air inlet and a closed position sealing the valve body against flow of air into the valve body through the air inlet. The float assembly includes a float adapted to pivot within a predetermined range of motion in relation to a longitudinal flow axis through the valve body. The float assembly has a cavity for receiving the pivot butt and adapted to pivot on the pivot butt. A bonnet is positioned over the float and has a sealing surface. A float seal is carried by the float and is adapted to seal against the sealing surface of the bonnet for preventing passage of water out of the valve body through the air inlet. The pivoting movement of the float is adapted to level the float and the float seal to the sealing surface of the bonnet in response to non-axial movement of the check assembly in the valve body.
According to another aspect of the invention, the float includes a conical float stem and a float spring for resisting movement of the check assembly into a position wherein the float seal seals closed the air inlet.
According to another aspect of the invention, the float spring is adapted to compress into the position where the float seal seals the closed air inlet at a water pressure in the valve of 2 psi.
According to another aspect of the invention, the check spring is adapted to compress into the position where the check assembly allows the water to flow through the valve at a water pressure in the valve of 4 psi.
According to another aspect of the invention, the float spring is adapted to compress into the position where the float seal seals the closed air inlet at a water pressure in the valve of 2 psi and the check spring is adapted to compress into the position where the check assembly moves into a position allowing the water to flow through the valve at a water pressure in the valve of 4 psi.
According to another aspect of the invention, the cavity in the float defines an annular taper, and the pivot butt is shaped to define an annular taper corresponding to the annular taper of the cavity in the float. The pivot butt has a width sufficiently less than a width of the cavity in the float to permit the pivot butt to move pivotally in the cavity of the float to accommodate misalignment of the check assembly in the valve body.
According to another aspect of the invention, the width of the cavity in the float and the width of the pivot butt vary sufficiently to allow radial movement of the pivot butt in the cavity in the float of between 0.5 and 2 degrees.
According to another aspect of the invention, the bonnet includes an annular rib adapted to seal against a top side of the float seal.
According to another aspect of the invention, a spill-resistant vacuum breaker valve is provided that includes comprising a valve body having a water inlet, a water outlet; and an air inlet and a check assembly positioned in the valve body and movable between an open position for allowing water to flow into the valve body through the water inlet and out of the valve body through the water outlet, and a closed position for preventing water from flowing out of the valve body through the water outlet. The check assembly includes a check poppet, a spring positioned on the check poppet and a spring retainer positioned over, and maintaining the spring under compression on the check poppet, the spring retainer including a co-axial pivot butt. A float assembly is positioned in the valve body between the check assembly and the air inlet and movable by movement of the check assembly between an open position allowing air to enter the valve body through the air inlet and a closed position sealing the valve body against flow of air into the valve body through the air inlet. The float assembly includes a float adapted to pivot within a predetermined range of motion in relation to a longitudinal flow axis through the valve body and has a cavity for receiving the pivot butt. The pivot butt is adapted to pivot on the pivot butt, and a bonnet is positioned over the float and has an annular sealing rib. A float seal is carried by the float and is adapted to seal against the sealing surface of the bonnet for preventing passage of water out of the valve body through the air inlet. The float includes a float spring for resisting movement of the check assembly into a position where the float seal seals closed the air inlet. The float spring is adapted to compress into the position where the float seal seals the closed air inlet at a water pressure in the valve of 2 psi and wherein the check spring is adapted to compress into the position where the check assembly moves into a position allowing the water to flow through the valve at a water pressure in the valve of 4 psi. The pivoting movement of the float is adapted to level the float and the float seal to the sealing rib of the bonnet in response to non-axial movement of the check assembly in the valve body.
According to another aspect of the invention, the cavity in the float defines an annular taper, and the pivot butt is shaped to define an annular taper corresponding to the annular taper of the cavity in the float. The pivot butt has a width sufficiently less than a width of the cavity in the float to permit the pivot butt to move pivotally in the cavity of the float to accommodate misalignment of the check assembly in the valve body.
According to another aspect of the invention, the width of the cavity and the width of the pivot butt vary sufficiently to allow radial movement of the pivot butt in the cavity of between 0.5 and 2 degrees.
According to another aspect of the invention, the check assembly includes an annular check guide positioned in the body of the vacuum breaker valve, a check housing, a check poppet, a check spring and a spring retainer mounted for axial movement in the check guide between water flow and non-flow positions.